Chipload Calculator

Calculate the correct CNC feed rate from chipload, RPM, and number of flutes — or find the chipload from your current parameters.

Feed Rate Calculator

Feed Rate
90
in/min (IPM)
Feed Rate = Chipload × RPM × Flutes

Recommended Chiploads by Material (Carbide End Mills)

Values in inches per tooth. Click any row to load the typical chipload into the calculator.

Material 1/8" End Mill 1/4" End Mill 1/2" End Mill
Aluminum (6061) 0.001–0.003 0.002–0.005 0.003–0.007
Aluminum (Cast) 0.001–0.002 0.002–0.004 0.003–0.006
Brass 0.001–0.002 0.002–0.004 0.003–0.005
Bronze 0.001–0.002 0.001–0.003 0.002–0.004
Mild Steel (1018) 0.0005–0.001 0.001–0.003 0.002–0.004
Medium Steel (1045) 0.0005–0.001 0.001–0.002 0.002–0.003
Alloy Steel (4140) 0.0003–0.001 0.001–0.002 0.001–0.003
Tool Steel (A2/D2) 0.0003–0.0008 0.0005–0.0015 0.001–0.002
Stainless Steel (304) 0.0005–0.001 0.001–0.002 0.001–0.003
Stainless Steel (316) 0.0003–0.001 0.001–0.002 0.001–0.002
Titanium (6Al-4V) 0.0003–0.0008 0.0005–0.001 0.001–0.002
Plastics (Acrylic) 0.002–0.005 0.003–0.007 0.005–0.010
Plastics (Delrin / HDPE) 0.003–0.006 0.004–0.008 0.005–0.012
Wood (Hardwood) 0.003–0.005 0.004–0.008 0.006–0.012
Wood (Softwood / MDF) 0.004–0.007 0.005–0.010 0.008–0.015
FR4 / G10 (PCB) 0.001–0.002 0.001–0.003 0.002–0.004
Carbon Fiber (CFRP) 0.001–0.003 0.002–0.004 0.003–0.005

Understanding Chipload

What is Chipload?

Chipload (also called chip thickness or feed per tooth) is the amount of material each cutting edge removes per revolution. It's the single most important parameter for tool life, surface finish, and cut quality.

Chipload = Feed Rate / (RPM × Flutes)

Feed Rate = Chipload × RPM × Flutes

Why Chipload Matters

  • Too low (rubbing) — the tool rubs instead of cutting, generating heat. This causes premature wear, work hardening in metals, and melting in plastics. A common beginner mistake is running too slow "to be safe" — this actually damages the tool faster.
  • Too high (overloading) — excessive force on the cutting edge leads to chipping, deflection, poor surface finish, or tool breakage.
  • Correct chipload — each flute takes a proper bite, heat goes into the chip (not the tool), and you get good surface finish with long tool life.

Chipload Rules of Thumb

  • Larger tools can handle larger chiploads — a 1/2" end mill runs roughly 2–3× the chipload of a 1/8" end mill in the same material
  • Fewer flutes = larger chipload per tooth at the same feed rate (more chip clearance)
  • For slotting (full-width cuts), reduce chipload by 30–50% compared to side milling
  • When in doubt, start at the low end and increase feed rate until you get good chips

Chipload vs Chip Thinning

The chiploads in the table above assume a radial depth of cut (stepover) of 50% or more of the tool diameter. When taking lighter radial cuts, the actual chip thickness is thinner than the programmed chipload, so you need to increase the feed rate to compensate. This is called chip thinning and is especially important for high-speed machining strategies like adaptive/trochoidal milling.

Verify Before You Cut

Once your feeds and speeds are dialed in, use CutViewer to visualize the complete toolpath in 3D.

Launch CutViewer

Frequently Asked Questions

How do you calculate feed rate from chipload?

Feed rate = RPM × number of flutes × chipload. For example, a 2-flute end mill at 18,000 RPM with a 0.002-inch chipload feeds at 18,000 × 2 × 0.002 = 72 inches per minute.

How do you calculate chipload?

Chipload = feed rate ÷ (RPM × number of flutes). A 3-flute end mill feeding at 60 IPM and 10,000 RPM has a chipload of 60 / (10,000 × 3) = 0.002 inches per tooth.

What happens if the chipload is too low?

The cutter rubs instead of cutting. That builds heat, dulls the edge quickly and can work-harden materials like stainless steel. Raise the feed rate or lower the RPM.

What happens if the chipload is too high?

Each tooth takes a bigger bite than the tool can handle, which increases deflection and can chip or break the cutter. Lower the feed rate or increase the RPM.

More Free CNC Tools

G-Code Reference Guide

Complete reference for G-code and M-code commands used in CNC machining. Each command includes a description, syntax, and example.
Tap & Drill Size Chart

Complete tap drill chart for UNC, UNF, and Metric threads with tap drill sizes, decimal equivalents, and clearance drills.
SFM Calculator

Convert between surface feet per minute (SFM) and RPM for any tool diameter. Includes recommended surface speeds for 20+ materials.
Stepover Calculator

Calculate cusp height from ball nose stepover and tool diameter. Visual diagram shows scallop profile for any stepover percentage.
G-Code Viewer & Simulator

Open .nc, .gcode or .tap files and check the 3D toolpath before you cut.